Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1988-10-11
1990-07-31
Wong, Peter S.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 42, 310 89, 29596, H02K 500, H02K 1514
Patent
active
049452703
DESCRIPTION:
BRIEF SUMMARY
INDUSTRIAL FIELD
This invention relates to a moisture drain structure for a dynamoelectric machine and a manufacturing method therefor and, more particularly, to a moisture drain structure for an electric motor of an engine starter and a manufacturing method therefor.
BACKGROUND ART
FIG. 1 illustrates one example of a moisture drain structure disposed at the rear portion of an engine starter motor. The starter motor illustrated in FIG. 1 comprises a d.c. motor armature 1 having a rotary shaft 2, an armature core 3 mounted on the rotary shaft 2 and a commutator 4 mounted on the rotary shaft 2. The starter motor also comprises a housing 5 including a magnetic yoke 6 and an end or rear bracket 7 connected to the magnetic yoke 6 by a well-known spigot joint structure 8. The end bracket 7 has brush assemblies 9 secured on its inner end surface by bolts 10 so that the brush assemblies 9 are maintained in a sliding pressure contact relationship with the commutator 4. The end bracket 7 also supports a bearing 11 which rotatably supports one end of the rotary shaft 2 of the armature 1.
In order to drain moisture captured within the motor housing 5, the startor motor 1 is also provided with a drain tube 12 inserted into a through hole 13 formed in the bottom rear end of the housing 5 of the startor motor 1. The illustrated drain tube 12 is made of rubber and has on the inner surface thereof a labyrinth structure 14 for preventing the ingress of moisture from below. The drain tube 12 is held in the hole 13 by a flange 15 formed at one end thereof.
According to the above-described moisture drain structure of the conventional design, the through hole 13 must first be formed in the rear bracket 7, and then the rubber drain pipe 12 must be inserted from the interior of the bracket 7. Thus, during the manufacture of the dynamoelectric machine, in addition to machining the rear bracket 7 for the spigot joint 8, the machining of the bracket 7 for the moisture drain through hole 13 must be done by a reamer or the like. Also, the rubber drain tube 12, which is a separate part, must be assembled into the through hole 13. Therefore, the number of manufacturing steps and the number of parts are relatively large, resulting in relatively high cost.
DISCLOSURE OF INVENTION
Accordingly, an object of the present invention is to provide a moisture drain structure for a dynamoelectric machine that can be easily manufactured at low cost.
Another object of the present invention is to provide a method for manufacturing a moisture drain structure for a dynamoelectric machine that allows the easy and quick manufacture of the moisture drain structure at low cost.
According to the moisture drain structure for a dynamoelectric machine of the present invention, the housing of the dynamoelectric machine includes a spigot joint for connecting housing sections. The spigot joint includes at least two joint elements which are thinly machined portions of the housing section walls to be overlapped with each other. The rear bracket of the motor housing section has a moisture drain conduit formed integrally with the bottom wall of the housing by casting, for example. The moisture drain conduit extends substantially along the outer surface of the housing and defines therein a moisture drain channel through which the moisture within the housing drains. One end of the moisture drain conduit is open in the axial direction of the motor. The other end is closed in the axial direction but is communicated with the interior of the housing through a hole which is formed in the spigot joint element of the housing. The top wall of the moisture drain channel is defined by the housing wall. The top wall surface of the drain channel is not on the same plane in which the outer surface of the housing wall lies, but is located above the plane including the housing outer surface by a distance at least equal to the thickness of the spigot joint element of that housing section.
According to the moisture drain structure of the present invention, the drain conduit comm
REFERENCES:
patent: 4336473 (1982-06-01), Wetters et al.
patent: 4491754 (1985-01-01), Gotoh
patent: 4808871 (1989-02-01), Morishita et al.
LaBalle C. E.
Mitsubishi Denki & Kabushiki Kaisha
Wong Peter S.
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